What are the four elements of the world?

According to the concepts of the ancient Greek philosophers, the world consists of four elements, which are known as "water, fire, air and earth". This was originally the creation of Empedocles, but Aristotle discussed the nature and transformation of these four elements in detail in his "On Generation and Destruction", forming a vast system. According to today's conception, the four elements represent all the forms of the material world visible to the naked eye: solid (earth), liquid (water), gas (air), and plasma (fire).

But then again, the "elements" Aristotle had in mind were not "elements" in the modernized sense; in fact, he spent a great deal of time arguing how they were created "in a circle" (the "circle"), and how they were created "in a circle" (the "circle"). In fact, he spends a lot of time arguing how these elements are generated "in a circle" (which is definitely similar to the Chinese doctrine of the five elements). Since the Middle Ages, alchemists have added three more things to the list of elements through tireless practice: sulfur, mercury and salt. It wasn't until Boyle published his famous book, The Skeptical Chemist, in 1661, that this gave a more modern definition of an element: an element is the simplest unmixed substance, which can't be further made up of other substances.

Gas was the first of the four elements to be kicked out. Since 1674, people have realized that air seems to be divided into two types, one that supports combustion and breathing, and another that seems to be dead. 100 years later, the Englishman Priestley formally discovered oxygen (which he then called "deflagration gas.") The Swedish Scherrer also discovered oxygen a year earlier. The Swede Scherrer had made the same discovery a year earlier, but published it later), and had isolated at least eight different gases from air. Apparently the so-called air is actually a mixture, not to speak of elements.

Next, Lavoisier, the heaviest hitter in the history of chemistry, made his debut, knocking the traditional theory of combustion to the ground and making it official that chemistry had finally parted ways with alchemy. Lavoisier told us that combustion is actually an oxidizing process, and the "earth" formed after combustion is actually nothing more than a compound of metal and oxygen. Under Lavoisier's light, "fire" and "earth" were removed from the list of elements, but of course this process was not a quick fix. In 1780, Marat, who was to become one of the leaders of the French Revolution, published an article trying to prove that fire was an element, giving Lavoisier Lavoisier. But he later paid an extremely painful price for this - he was guillotined by the revolutionary government in 1794. We'll talk more about that in a later rant.

That left only water among the four elements. Chemists discovered early on that burning a "combustible gas" (hydrogen) in air would eventually produce water. Cavendish heard about this from Priestley and conducted a series of experiments of his own to confirm it. These developments in turn reached the ears of James Watt, who was famous for having improved the vaporizer, and it immediately occurred to him that it could be proved backwards that water was made up of two gases. Watt wrote an article and sent it to Priestley, asking that it be sent to the Royal Society, and Cavendish saw it and immediately completed his experiments. in January 1784 he pre-empted the reading of the paper before the Royal Society. Both men's articles were later published in the journal Philosophical Correspondence in 1784.

A debate about water then began.